1. Field of the Invention
The present invention relates to an organic-inorganic hybrid transparent hydrogel complex for fire retardant glass, a fire retardant glass assembly using the same, and a manufacturing method thereof.
2. Description of Related Art
Fire retardant glass is used to prevent flames from spreading to the interior of a building in the event of a fire.
In general, a fire retardant glass consists of at least two panes of glass and a fire retardant material interposed therebetween. Examples of fire retardant glass include float glass and tempered glass. The float glass is vulnerable to external impact, while the tempered glass provides the required transparency, but it cannot provide the required functionalities to cope with external environments.
Suitable fire retardant materials for the fire retardant glass should have excellent fire retardancy and external appearance. That is, fire retardancy depends on the rate of evaporation of water contained in the fire retardant material and the fire retardant material's capacity to form an insulating layer when it is exposed to the flame. Therefore, in order to achieve the required fire retardancy, the fire retardant material must have high water content and preserve the insulating layer formed during heating. Moreover, it should have excellent adhesion with glass and self-supporting performance. Furthermore, with regard to the appearance, it should have a transparency like a pane of glass and have no optical distortion of objects. In addition, it should have high physical and chemical properties such as excellent low-temperature and high-temperature stability and no discoloration by light.
Conventional resin compositions used as a fire retardant material include organic polymer hydrogels and inorganic silicate hydrogels. The organic polymer hydrogel is advantageous in that it has higher water content than the inorganic hydrogel, but it is disadvantageous in that it is easily decomposed by heat. To overcome the disadvantage, there has been an attempt to thicken the resin layer, but it is difficult to ensure a homogeneous reaction due to increased thickness of the resin layer. Further, if the resin layer becomes thick, it may cause optical distortion so that an object at the opposite side of the fire retardant glass may be seen as distorted by a heterogeneous reaction of the resin layer. Moreover, when the organic polymer hydrogel is exposed to flame, its local temperature may be increased by the heterogeneous reaction inside the resin layer. Meanwhile, since the inorganic hydrogel contains an inorganic material and has low water content, it has drawbacks that the temperature at the opposite side is considerably increased at the initial stage of heating. Further, the unit production cost is very high because the raw material is expensive and has high solid content. Besides, since the viscosity of the resin composition is high and the stability at room temperature is low, it requires special care and equipment, and the manufacturing process is complex.
Examples of such fire retardant glass assemblies using resin compositions are disclosed in U.S. Pat. No. 4,830,913 and Korean Patent Publication No. 1996-0005270. Such fire retardant glass assemblies are generally manufactured by filling a resin composition between at least two glass plates separated by spacers. Here, it is necessary to easily inject the resin composition into the space formed by the glass plates regardless of the thickness and shape of the space.
As typical examples of the resin compositions used as the fire retardant materials, U.S. Pat. No. 4,830,913 discloses a resin composition comprising a water-soluble salt, an acrylic monomer, water, and an anticorrosive compound, and U.S. Patent Application No. 2003/0004247 discloses a resin composition comprising a water-soluble salt, an acrylic monomer, and a cross-linkable fire retardant agent.
However, each of the above-described resin compositions contains an organic polymer as a main component, and thus the fire retardancy is reduced compared to the hydrogel containing an inorganic material as a main component, and the resin layer should have a large thickness to exhibit excellent fire retardancy, which results in the increase of the product weight. Moreover, when the thickness of the resin layer is increased, the deviation in heat transfer into the resin layer is increased, which causes the optical distortion, in which an object at the opposite side of the fire retardant glass is seen distorted by heterogeneous reaction of the resin layer.
U.S. Pat. No. 5,565,273 discloses a fire retardant glass assembly comprising an inorganic silicate hydrogel as a resin composition. Since the hydrogel used in this patent contains an inorganic material as a main component, the entire specific gravity is high. Moreover, since the glass assembly comprises a sealed insulating glass with several panes of glass, the weight of the product is increased. Furthermore, it is necessary to coat the glass surface with a separate compound to improve the adhesion with the glass. In addition, since the resin composition itself containing silicate as a main component itself has its intrinsic viscosity, it is difficult to inject the resin composition at normal pressure, and it will lengthen the time for degassing process. Additionally, since the storage stability at room temperature of the silicate solution before injection is low, it requires special handling and storage.
U.S. Pat. No. 6,379,825 discloses a method of forming a uniform and transparent fire-resistant glazing panel by partially drying a mixed solution of a silicate resin compound used as a fire retardant material, applying the resulting solution on the glass surface, and applying heat and pressure to the glass surface. However, the manufacturing processes such as the drying process and insulating process are complex and, since the resin layer has low water content and small thickness, it can show the fire retardant function only when it is composed of several resin layers and several panes of glass.
Therefore, it is necessary to develop a fire retardant material having excellent physicochemical properties such as long-term durability and weather resistance as well as the properties required for the fire retardant glass such as long-term transparency, flame-retardant performance, and thermal insulation performance, and a method of manufacturing a fire retardant glass assembly using the same by a simplified process.